High contrast negatives for line and half-tone work are important in the practice of the graphic arts. Development of such films is carried out for maximum contrast in special developers which are known in the art as `lith` developers. In conventional lith developers, high contrast is achieved using the lithographic effect, (also referred to as infectious development) as described by Yule in the Journal of the Franklin Institute, 239, 221-230. This type of development is believed to proceed autocatalytically. To achieve the lith effect in development, a low, but critical concentration of free sulfite ion is maintained by using an aldehyde bisulfite adduct, such as sodium formaldehyde bisulfite, which acts as a sulfite ion buffer. The low sulfite ion concentration is necessary to avoid interference with the accumulation of developing agent oxidation products. Such interference can result in cessation of infectious development. The developer typically contains only a single type of developing agent, namely, a developing agent of the dihydroxybenzene type, such as hydroquinone, but auxiliary developers are known in the art.
Conventional lith developers suffer from serious deficiencies which restrict their usefulness. For example, the developers tend to exhibit low capacity as a result of the fact that it contains hydroquinone as the sole developing agent. Also, the aldehyde tends to react with the hydroquinone to cause undesirable changes in development activity. Furthermore, the low sulfite ion concentration is inadequate to provide effective protection against aerial oxidation. As a result, conventional lith developers lack stability and tend to give erratic results depending on the length of time that they have been exposed to the air.
An alternative to the use of conventional lith developers is disclosed in Nothnagle, U.S. Pat. No. 4,269,929, `High Contrast Development Of Photographic Elements`. As described in this patent, high contrast development of photographic elements is carried out in the presence of a hydrazine compound with an aqueous alkaline developing solution which has a pH of about 10 and below 12 and contains a dihydroxybenzene developing agent, a 3-pyrazolidone developing agent, a sulfite preservative, and as a contrast-promoting agent, an amino compound. U.S. Pat. No. 4,269,929 describes the use of a very wide variety of amino compounds as contrast-promoting agents. In particular, it discloses the use of both inorganic amines, such as the hydroxylamines, and organic amines, including aliphatic amines, alkyl amines, alkanol amines, aromatic amines, cyclic amines, mixed aliphatic-aromatic amines, and heterocyclic amines. Primary, secondary and tertiary amines, as well as quaternary ammonium compounds, are included within the broad scope of the disclosure.
High contrast developing compositions which contain amino compounds as contrast-promoting agents which are intended for carrying out development in the presence of a hydrazine compound are also disclosed in U.S. Pat. Nos. 4,668,605 and 4,740,452. U.S. Pat. No. 4,668,605 describes developing compositions containing a dihydroxybenzene, a p-aminophenol, a sulfite, a contrast-promoting amount of an alkanolamine comprising an hydroxyalkyl group of 2 to 10 carbon atoms, and a mercapto compound. The developing compositions of U.S. Pat. No. 4,740,452 contain a contrast-promoting amount of certain trialkyl amines, monoalkyldialkanol amines or dialkylmonoalkanol amines.
The inherent disadvantages of incorporating amino compounds as contrast-promoting agents in developing compositions have been recognized in the prior art, and proposals have been made heretofore to overcome these disadvantages and other problems by incorporating the amino compound in the photographic element. In particular, the use of amino compounds as incorporated boosters, has been proposed in Japanese Patent Publication Nos. 140340/85 and 222241/87. In Publication No. 140340/85, it is alleged that any amino compound can be utilized as an `incorporated booster,` while Publication No. 222241/87 is directed to the use of amino compounds defined by a specific structural formula as incorporated boosters. Publication No. 222241/87 points to some of the problems involved in following the teachings of Publication No. 140340/85, including generation of `pepper fog`. Pepper fog may be described as black dots appearing on the developed film which do not correspond to the exposed image. The effect can appear as though pepper has been spilled on the film, hence the name.
A photographic system depending on the joint action of hydrazine compounds which function as nucleators, and amino compounds which function as contrast-promoting agents is an exceedingly complex system. It is influenced by both the composition and concentration of the nucleator and contrast-promoting agent and by many other factors including the pH and composition of the developer and the time and temperature of development. The goals of such a system include the provision of enhanced contrast, together with excellent dot quality and low pepper fog.
U.S. Pat. No. 4,237,214, Mifune et al., describes a lith system utilizing heterocyclic quaternary salts in addition to arylacylhydrazine.
British Patent 1,581,963, assigned to Fuji, claims increased speed and contrast when thioamide compounds, such as benzothiazolinethione, are present in addition to the hydrazide.
U.S. Pat. No. 4,241,164, Mifune et al., claims increased sensitivity when the emulsion contains hydroxytetraazaindene.
U.S. Pat. No. 4,937,160 discloses use of hydrazides with amino boosters.
U.S. Pat. No. 4,914,003, Yagihara et al., describes a system using a hydrazine and a amine compound of general formula: ##STR1##
U.S. Pat. No. 4,975,354, Machonkin et al., describes a system using a hydrazine and certain secondary and tertiary amino compounds of general formula: ##STR2##
EP 0,324,391, Takamuki, describes a high contrast silver halide emulsion containing 3-pyrazolidone and di- or trihydroxybenzene compound which is developed in a developer containing a di- or trihydroxybenzene compound, sulfite, and an amino compound in the presence of a hydrazide.
U.S. Pat. No. 5,139,921, Takagi, describes a process of forming a high contrast image with a silver halide material containing a hydrazide and a nucleation accelerator (an amino containing mercaptan, mercaptotetrazole, oxazole, oxadiazole, triazole, imidazole, thiadiazole, diazole, triazolopyrimide, or purines) in a developer of pH 9.6 to 11.0.
U.S. Pat. No. 4,956,260, Nakamura, describes a photothermographic system using five or six membered nitrogen containing heterocyclic compounds as an antifoggant or development accelerator.
European Patent 0420005, Takahiro, describes an ultrahigh contrast silver halide material containing a hydrazide nucleating agent and a development inhibiter.
European Patent 0539925, Onodera, describes a high contrast silver halide material containing substituted phenyl hydrazines.
U.S. Pat. No. 4,693,956, Marchesano, describes a process for forming a high contrast image comprising a silver halide material containing a hydrazine, antifoggant, and contrast promoting agent within the classes of benzotriazole and benzimidazole compounds.
U.S. Pat. No. 2,857,276, Land et al., describes a diffusion transfer-reversal photographic process wherein an aqueous solution containing cyclic imides are used to form water soluble complex silver salts.